This invention relates to mattresses and more particularly to articulated innerspring mattresses for adjustable beds. Hospital beds are frequently made with four sections that may be adjusted relative to one another for comfort and therapeutic purposes. Beds of this type are now often found in homes as well. Mattresses for these adjustable beds should have all of the body supporting properties of flat mattresses while also being bendable at the joints of the articulated sections. Because of the additional requirements put on mattresses to make them bendable at the joints, prior art mattresses made for these beds have a very short useful life. They rapidly lose their support at the joints and at the edges.
Conventional innerspring mattresses are supplied with sturdy border wires along top and bottom edges to prevent sagging. Further support may be provided by side edge supports between top and bottom wires. The individual coils are further stabilized by top and bottom longitudinal straps joining all the coils in longitudinal rows. These stabilizing and reinforcing structures make the mattress uniformly resilient in the direction required to support the horizontal body.
However, these same structures resist bending as required on an articulated bed. Consequently, they are not provided on mattresses of the prior art designed for articulated beds. As a result, articulated mattresses of the prior art have very short useful lives and do not provide the uniform body support necessary for this application. The springs distort at the folds from bending and at the edges from the reduced coil support and extra forces from sitting on the edge of the bed.